The present invention relates to a process for the plutonium decontamination of an organic solvent, particularly a spent organic solvent such as tributylphosphate, which has been used for uranium-plutonium separation during the reprocessing of irradiated nuclear fuels.
It is known that organic solvents such as tributylphosphate, which have been used for the reprocessing of irradiated nuclear fuels are essentially degraded by alpha radiolysis and by hydrolysis. Moreover, a variable quantity of plutonium is also held back in the spent organic solvent. When the solvent is tributylphosphate, plutonium is held back in it probably due to the presence of small quantities of dibutylphosphoric acid, which forms with the plutonium complexes which are more stable than plutonium-tributylphosphate complexes.
When these spent solvents are purified by washing with alkaline solutions, the solvent is regenerated, but washing solutions are obtained which have a by no means negligible alpha radioactivity. This leads to large quantities of alkaline radioactive effluents and consequently increases the volume of the radioactive waste to be processed.
To obviate this disadvantage, it is desirable to recover as quantitatively as possible the plutonium present in the spent organic solvents before they undergo the basic regeneration treatment.